The present invention relates to polyalkoxysilylenolethers, for example, methyldimethoxyisopropenoxysilane and a method for making such materials. More particularly, the present invention relates to the preparation of methyldimethoxyisopropenoxysilane by initially forming methyldimethoxysilane from methyldichlorosilane and methanol and thereafter converting the methyldimethoxysilane by reacting it with acetone in the presence of a transition metal catalyst.
As shown in the copending application of White et al. RD-13275, filed concurrently herewith and assigned to the same assignee as the present invention, methyldimethoxyisopropenoxysilane can be used as a scavenging silane for hydroxy functional groups to prepare room temperature vulcanizing compositions under substantially anhydrous conditions with a mixture of a silanol-terminated polydiorganosiloxane and fumed silica filler. Silylenolethers have been prepared, usually from ketones and chlorosilanes, in the presence of bases, as shown by H. O. House et al, Journal of Organic Chemistry, 34, 2324 (1969). Additional procedures are shown by H. Sakurai et al, Tetrahedron Letters, 31, 2671 (1971) and R. Calas, Journal of Organometallic Chemistry, 200, 11 (1980), utilizing ketones and silicon hydrides in the presence of a variety of transition metal catalysts.
The present invention is based on the discovery that polyalkoxysilylenolethers of the formula, ##STR1## can be made by heating the corresponding polyalkoxysilane and ketone in the presence of a transition metal catalyst, where R is a C.sub.(1-13) substituted or unsubstituted monovalent hydrocarbon radical, R.sup.1 is a C.sub.(1-8) alkyl radical, R.sup.2 is selected from hydrogen, R.sup.1 radicals and mixtures thereof, a is equal to 1 or 2, b is equal to 0 or 1, and the sum of a+b is equal to 1 or 2.